Torque responsive variable pitch propeller



Dec. 9, 1947.

D. G. LILLEY TORQUE RESPONSIVE VARIABLE PITCH PROPELLER Filed March 15,1944 DA N/EL 2 Sheets-Sheet 1 INVHVTOR. G. LILLEY Afforney Dec. 9,1947.D. e. LlLLEY 3 .320

TORQUE RESPONSIVE VARIABLE PITCH PROPELLER Filed March 13, 1944 2Sheets-Sheet 2 INVENTOR. DAN/EL G L/LLEY Patented Dec. 9, 1947 TORQUERESPONSIVE VARIABLE PITCH PROPELLER Daniel G. Lilley, Denver, Colo.

Application March 13, 1944, Serial No. 526,273

Claims. 1

This invention relates to improvements in torque responsive, governorcontrolled, variable pitch propeller mechanisms, and is a continuationin part of copending application, Serial No. 352,352, filed August 13,1940, Patent No. 2, 346,979.

Whether the device be a boat floating on the medium of Water, a kite,balloon or an aeroplane supported in the medium of air, if any of thesedevices are moved head-on against such me diums, or if they are merelyheld against movement with respect to a land station by any meanswhatsoever, said mediums when traveling with.

respect to the land station, will also be forced to travel with respectto such devices. This is the method used in flying a kite.

Therefore, so longas a plane travels into a head wind and makesprogress, or merely maintains a definite position with respect to a landstation by propeller effort, the wind will be forced to travel head-onrelative to the plane, and since the propeller is carried by the plane,the wind must travel windmill fashion relative to the propeller at thesame rate of speed as though the propeller were mounted for operationupon the land station.

, Careful consideration shouldbe given to the statements in the abovetwo paragraphs, which form the basis for this invention. If a plane willnormally travel in air that is still at the rate of 180 M. P. H.withrespect to aland station, andis caught in a 70 M. P. H. head wind,it will be slowed down to approximately 110 M. P. H. with respect to theland station, and the wind will be traveling in the opposite directionat the rate of 70 M. P. H. relative to the land station and towards theono-omingplane. Therefore, we must come to the conclusion that the windwill blow head-on relative to the plane and propeller at the same rateof speed it blows relative to the land station.

If the above were not so, th plane would not be slowed down to 110 .M.P. H. with respect to the land station, nor could it have normal (180 M.P. H. air speed) when traveling only 110 relative to the land stationunless the air did travel 70 M. P. H. head-on relative to the plane, andincidentally windmill fashion relative to the propeller.

If the headwind did nottravel windmill fashion relative tothe propeller,it could not travel relative to the ship to make up part of the shipsair speed and act as a drag to slow down the progress ofthe ship to 110M. P. H. relative to the land station. "This voluntary movement of aircauses a lossin the rate of blade hitting speed relative to;

(Cl. fill-135.6)

the air, resulting in a loss of propeller thrust efll ciency, and whichthrust efliciency can be rethe case of the head wind on the one hand,and

the displacement of airby the propeller on the other hand, are able toproduce a thrust force, one upon the other only in the proportion oftheir respective speeds.

. Rule 2. Tail winds which are traveling against the tra-ctive effortside of the whirling propeller blades represent a case of two parallelmediums of force directed in opposite directions, which combine toproducea thrust force and rate of plane travel equal in value to thecombined rates of travel of said two parallel forces. When these tworules are applied to aeroplane propulsion, it will be found, when thpropeller is restricted to operate at a constant number of R. P. M.,that head winds will cause a drop in propeller torque value, and a tailWind will cause a drop in ship drag value, either of which will cause adrop in torque value upon the engine, and result in a correspondingloss-in plane air speed. While suchtorque loss in a tail wind may be ofa temporary nature, the torque loss caused by a head wind will obtain aslong as the wind continues, unless the pitch-is'increased and for thenumber of propeller R. P. M. is increased surficiently to compensate forthe head wind velocity. Head winds blowing windmill fashion into apropellerwill cause a loss in the propeller thrust and torque value uponthe-engine of from one to as much as 20% or more, resulting in a similarloss in plane velocity and air speed unless the pitch is increasedand/or' the number of engine R. P. M. is increased, as above mentioned.Said loss in thrustwill be set upinthe proportion of wind velocity totherotational speed of the propeller.,- H

.Where the medium of either water or air is stillrelative toa station:on the earths surface, and where a propelling mechanism is employed tomove a boat orplane relative to said mediums,

mept orthemovement of the boat or plane rela- 3 tive to the medium, andrelative to the land station, and so long as the air is still withrespect to the land station, a propeller operated at constant speed willproduce a uniform rate of movement of the plane or boat with respect tothe land station, in which operation only the two relative movements areinvolved.

The instant these mediums of air or water begin moving relative to theland station, and parallel to the line of boat or plane movement, athird relative movement is set up with respect to the boat or plane andthe propelling mechanism. While this third relative movement cooperatesto maintain relative ship and air speed even though the ship loses speedrelative to the land station, the effects of this same third relativemovement upon the thrust efiiciency of the propeller, where the latteris operated at constant speed, has just the opposite eirect, and isdiametrically opposed in its effect upon thrust efficiency underconstant speed propeller operation. There is a point beyond which thiscondition cannot be allowed to exist depending upon the velocity of thewind, if safe relative ship and air speed is to li -maintained.

The fact that this third relative movement, set up by headwinds in theimmediate vicinity of the flying plane, normally causes an increase inblade pitch due to the automatic action of the centrifugal governorproves that a change in the interaction between the propeller and theair medium takes place, causing an unloading of the engine, due to adrop in propeller torque value, otherwise the governor would not operatein a manner to cause an increase in blade pitch out of coordination withplane air speed and velocity.

The interaction between the blades and the air medium would indicatethat the speed responsive governor is also a torque responsive device,which derives its initiative for operating the blade moving motorcontrol means from variations in propeller torque value upon the R. P.M. of the engine, which fact will become clearly apparent when theoperation of the following mechanism .is more fully explained andunderstood.

Provided the above-mentioned third relative movement comprised of windvelocity will cause variations in propeller torque value upon theengine, together with a resulting loss in plane veloc-. ity and airspeed, then in the above-mentioned case with an air speed of 180 M. P.H., let us say the safe minimum air speed of a heavil loaded plane is100 M. P. H. This would leave only the very slight margin of M. P. H.between minimum safe plane air speed and plane velocity of 110 M. P. H.

The above mentioned margin of safety'of 10 M. P. H. between minimum airspeed an iane velocity would be the same if the wind and planevelocities were both reduced say by 40 M. P. H. and it will be seen thatif plane velocity and air speed were at say 140 M. P. H. should thecraft encounter a 70 M. P. H. head wind, plane velocity would be reducedto 70 M. P. H., or 30 M. P. H.

Y below safe minimum air speed, which would be a dangerous planevelocity in the event of a sudden shift in wind direction. Here it willbe seen the real danger is in the ratio of wind velocity to planevelocity, and the number 1 of propeller .R..P. M. at the instant thewind is encountered,

also the factor of lapse of time before making an increase in Ditchand/or the number of engine and propeller R. P. M. under suchcircumstances.

Sucha condition might easily be set up, especially ity. Since it mightnot have much noticeable reaction upon the plane, it might go unobservedby the pilot, which conditio might be the begin nin of a serious loss inplane velocity and air speed.

Since the element of time may be such an important factor incircumstances similar to the last two above mentioned cases, it appearsimperative as a. safety factor, that. the number of engine and propellerR. P. M. provided for by the governor should be automatically increasedthe instant wind causes a predetermined drop in propeller torque valueupon the engine, to avoid the possibility of plane velocity dropping toa point below minimum plane air speed.

In cOnnection with the foregoing, it is well to keep in mind that airdensity will always be an integral factor, that for a given powerexpenditure, plane velocity and air speed will automatically be at arate corresponding to air density and ship drag resistance.

Obiects It is therefore an object of this invention to provide torqueresponsive, governor controlled propellers with means for automaticallyincreasing the number of propeller R. P. M. whenever wind velocitycauses propeller torque value upon the engine to drop below a givenpredetermined value.

It is an object of the invention to employ the blade pitch responsiveelement for the double purpose of limiting the blade pitch angle to apredeterminedvalue, and for operation as a propeller torque responsiveelement for automatically causing an increase in the number of propellerR. P. M. whenever the torque value of, the propeller upon the enginedrops below a given value, whereby a substantially constant propellertorque load upon the engine will be automatically maintained, and resultin a substantially constant predetermined rate of plane velocityirrespective of wind conditions.

A further object is to provide a pilot with means for determining planeair speed, ground speed, wind velocity and direction at any time, by thenumber of engine and propeller R. P. M. that is required to bring thepropeller under full torque load upon the engine, as indicated by theposition or action set up by the torque responsive element, and whichcan be employed as. a dependable air speed indicator either by itself oras a check against the orthodox air speed indicator.

It is an object of the invention to take advantage of changes inpropeller torque value upon the engine for automatically increasing thenumber of engine and propeller R. P. M. the instant said propellertorque value drops below a predetermined value, and for maintaining saidtorque at a substantially constant value simultaneously as the bladepitch is limited to a value commensurate with plane velocity and airspeed.

It is, an object of the invention to eliminate the dangerous-lapse oftime during which conditions above mentioned will be allowed to becomeset up unless means are provided for an immediate increase in the numberof propeller and engine R. P. M. for restoring the normal rateof bladehitting speed relative to the air, and to avoid the lapse of time duringwhich plane velocity and air speed will otherwise be allowed to dropback out siveelement, as well as a'blasde pitch limiting element, and toemploy said torque responsive element as an automatic means forindicating to the pilot when propeller torque drops below a givenpredetermined value, or for increasing the number of engine andpropeller R. P. M. automatically whenever such drops in propeller torquevalue occurs.

A further object ofthe invention is to provide automatic means, forstabilizing the operative characteristics of the governor, for alteringthe blade pitch in conformance with any changes in number of engine R.P. M., and plane drag resistance, whereby said governor will operate todecrease the blade pitch, whenever propeller torque value upon theenginereaches a pointabove mean value, to avoid overloading the engineunder any operating conditions, as during period of take-off and steepangles of climb.

It is a further object of the invention, to provide means forinterconnecting the governor control means with the engine throttlemechanism for maintaining a substantially coordinated and stabilizedrelationship between thesetwo elecally by the blade pitch responsivepitch limiting control element; or by a manually operable means. 7 I

Still another object of the invention is to provide means for makingquickchanges in the number of engine and propeller R. P. M. by eithermanual or automatic means, by providing means for interconnecting theengine throttle with the governor spring tensioning means forcoordinating and maintaining the operative characteristics in properrelationship between these two elements.

A still further object of the invention isto provide a means by which apilot may control the operation of the blade moving motor, by manualmeans for moving and holdin the'motor control means in adjusted positionagainst the action of the governor.

I Another object of the invention is to enable the operator to move thethrottle to increase the number of engine and propeller R. P. M., tomeet any emergency or maneuver requiring a sudden burst of speed,without fear of increasing the blade pitch out of coordination withplane velocity and plane drag resistance. A still further object of theinvention is to provide the pilot of a plane having a governorcontrolled propeller with a safety device, which when snapped intooperative position will operateto automatically maintain a rate of planevelocity with respect to a given land reference point at a valueequal tothe planes minimum rate of air speed.

Having thus explained the theory upon which this invention is based andset forth the objects thereof, the construction by means of which theobjects are attained will now be described in detail, and for thispurpose reference will be had to the accompanying drawings in which oneembodiment of the invention has been illustrated, and in [iii - Figure-4is a section taken on line 44, Figure 2; and v V Figure-5 is a viewshowing a hand and foot control for manual operation of the enginethrottle.

Referring now to the drawing and more particularly to Figure 1, whichshows the preferred form of the invention, reference numeral 5 shows aportion of the crank case wall from which a bottom wall 6 extendsforwardly and terminates in an end wall i. Reference numeral 8represents a part of the propeller drive shaft and this has a circular.flange 9 that is connected along its peripherial edge to the flange IUof the housing portion lea of the drive shaft. The part designated byreference-numeral Illa: is the rotor of the pitch adjusting motor whichis shown in Figure 3. A tubular shaft ll extends through an axialopening in the drive shaft and terminates in'a .threaded end portion l2to which a nut I 3 is connected. A spur gear i4 is nonrotatablyconnected with the tubular shaft. so as to be rotated therewith and thisgear corresponds to the spur. gear designated by the same number in theextension of Figure 1. I

In the, embodiment illustrated in Figure}, a gear pump Ida is carried bythe crank case a d a portion of Figure 1 has been broken away to showgear i5 that forms part of the gear pump which serves to maintain aconstant flow of oil for use. in operating the motor that changes thepitch of theprope ller blades, the rotor of which has been designated bylike. A ring gear [6 car ried by the drive shaft serves to operate thegear pump whenever the engine is running. The oil for use in operatingthe parts is contained in a sump ii from which a pipe I8 extends to theintake portlof the gear pump and a pipe l9 extends from the deliveryport of the pump to a pressure chamber 26 in the body 2| of a slidevalve which will be hereinafter more fully described. When the rotorI81; is turning. it'carries with it the tubular shaft I I because thetwo are held against relativerotation by means of splines. A ring gear22 is splined to the tubular shaft and cooperates 2; witha spur gear 23that is carried by the housing iealand which is nonrotatably' mounted ona shaft24 whose front end is threaded and engages in a threaded openingin the inner ball race .25 of a ball bearing whose outer ball race hasbeen designated by. reference numeral 26. There are two gearsZS and twothreaded shafts 24, which are operated in unison and therefore whenshaft 2-! turns in one direction, itmOVes the ball bear ing towards theleft and when it turns in the opposite direction it moves it towards theright; Two arms 2? arenonrotatably connected to a shaft 28 and extenddownwardly on opposite sides of the ball race 26'and have their lowerends at tached to the pivots 29 and therefore whenever the ball racemoves longitudinally, it will rock shaft ZBfaboutit-s axis. A lever 30has on end nonrotatably secured to the shaft 28 and has a connecting rod3i pivotally connected with its free end. The other endof thisconnectingrod is connected by means of apivot 32 with the free end-of alever 33 that is pivoted at 34, It is now evident that whenever the ballrace 25 moves to wards the right ortowards the left, the lever; 33,togetherwith the arm 35 which is integralthere: with will rock aboutpivot-34. The purpose of this lmovement will appear as the descriptionproceeds. Y q

Re ferring now to shaft. 28, it will be seen that this is journaled inbearings in link 35 that is pivoted at 31. This link permitsltheshpfi toinqye Se astoprevent any binding action due to the change of angle whenthe ball race 26 moves.

Since the ball race 26 is operated directly from the tubular shaft II,and since the latter by its rotation controls the pitch of the blade, itis evident that the movement of lever 33 corresponds to the pitchadjustment of the propeller blade and arm 35 serves as a pitch indicatorfor a purposethat will hereinafter appear. The valve body 2| has achamber 25 and has a central cylindrical opening 38' in which ispositioned a slide valve 39. Chamber 2|? is connected with the opening38 by means of ports 40 and M. The other'side of thevalve body isprovided with a longitudinally extending opening Ma that is incommunication with the cylindrical opening 33 through four ports whichhave been designated as a, b, c and d. The movable part of the slidevalve which has been designated by reference numeral 39, is providedwith annular recesses that have been designated by reference letters e,f, g, h and 2'. The wall of the valve body has two openings which havebeen designated by 425:: and 43$. These openings or ports are incommunication with conduits 42y and 43y respectively. When the engine isoperating with the parts in the position shown in Fig. 1, the pump willdraw oil from the sump l1 and discharge it through pipe 19 intocompartment 20 I from which it flows through the annular recess h andpasses through the port into the longit'udinal opening Ma from whence itreturns to the sump l'l. Extendin upwardly from the slide valve member39 is a shaft 44, which is provided directly above the valve with ashoulder 45, on which is positioned a cup 46. A helical spring 41 hasits lower end seated in the cup and its upper end in engagement with adisk 48 that is slidably mounted in the opening 49. This disk isprovided with two or more splines that engage in the spline grooves 50to hold it from turning. A hub t extends downwardly from the lower endof the disk and is slidably connected with the shaft 44. The uppersurface of the disk has two aligned fulcrums 52 on which the upper arm53 of a bell crank lever rests. The vertical arm of this bell cranklever has been designated by reference numeral 54. The bell crank leveris pivoted at 55 to the top of a spring bracket 564 This bracket isprovided with a screw 51 by means of which its upper end can be moved toand from the body of the slide valve assembly so as to change thedistance from the pivot 55 to the fulcrum 52 for a purpose which willhereinafter appear. Secured to the stationary part 58 of the engineframe is a centrifugal governor whose base has been designated byreference 59. R0- tatably mounted in the base is a sleeve 60 to whichthe upwardly extending brackets 6| are secured by suitable means such asthe nut 62. The brackets are nonrotatably connected with the sleeve andare provided at their upper ends with pivots 63 by means of which thegovernor weights 64 are attached. Each weight is provided with aninwardly extending arm 55 that engages in a groove on the outer surfaceof the member 66. The lower end of sleeve 65 has a bevel gear 61 that isengaged by another bevel gear 68 secured to the end of a shaft 69 whichextends to and is connected with a spur gear Ill that is C05 operativelyengaged with ring gear [6 as shown in Figure 1. Since ring I6 is securedto the.propeller shaft, it is evident that the governor will be rotatedat a speed corresponding to the propeller shaft speed.

Referringnowto Figure 2, itwill be seen that:

when the governor weights are thrown outwardly by centrifugal forces,they will moveshaft 44 and the slide valve 33 upwardly, therebycompressing spring 4-7, which, in this embodiment serves as i thegovernor control spring. Itis also evident that by changing theadjustment of the bell crank lever about its pivot 55, the operation ofthe governor can be adjusted.

A ringor nut TI is threadedly connected with the shaft 44 at a pointabove the arm 35, It will: be remembered that arm 35 can oscillate aboutthe pivot or shaft 34 and that its position is controlled by a mechanismthat moves in response to pitch adjustment. Carried by the inner part ofarm 35 is a pivot 12 which secures the adjustable arm 13 thereto. Thearm 13 is provided with a gear segment 14 that is engaged by a pinion 15secured to the shaft 16-. A handle 17 is connected with shaft 16 and bymeans of this handle the pinion 15 can be-turned, thereby imparting acorresponding movement to the arm 13; A sprin detent 78 serves to holdthe handle l1 and associatedparts in adjusted position.

Secured to the shaft 44 is a spool-like member 19 that is held fromlongitudinal movement, but permitted to rotate relative to the shaft bymeansof the bearings 83. This spool-like member will move upwardly anddownwardly in response to the action of the governor; A body 8| issecured to the machine in such a way as to be stationary with respect tothe slide valve body. The upper surface of this body is provided with acylindrical depression 82 for cooperative action with the adjustablemember 83 that can be turned about the pivot 84. Member 83 has anupwardly extending cylindrical portion 85 on which a handle 86 isrotatably mounted. This handle is held in position by means of a bolt 81and a nut 88. The body BI is provided with an opening extending from thelower surface thereof into the spherical depression and-positioned inthis opening is a plug 89 that is urged upwardly against the outersurface of member 83 by means of a spring 90. The plug 89 serves as abrake to hold the member 83 from rotation and whenever the handle 86 ismoved into the position shown in Figure 2, its front end 85a will engagein the groove of member 19 and hold the shaft 44 against the action ofthe centrifugal governor at the same time the operator or pilot canadjust the slide valve by turning handle 86 about the pivot 84. Thismeans therefore serves to take automatic control away from the governorand to substitute manual control. It also serves as a means for holdingthe control valve in any desired adjusted position. Normally, lever 85occupies one of the dotted line positions shown in Figure 4 and istherefore inoperative.

In Figure 2 which, it will be remembered, is a diagrammaticrepresentation, the arm '13 has been. shown in two positions, the one tothe right being a displacement intended to facilitate the descriptionand the understanding of the invention with tively connected with wormgear 91 that is secured to the shaft 98. Shaft 98 extends through ahousing 99 and is journaled in a bearing in the end closure I00. 'Shaft98 is provided within the housing with a square thread which has beendesignated by reference numeral IIlI. Surrounding the threaded portionII is a sleeve I62 that is provided on its upper surface with spacedlugs I03 between which an arm I04 is mounted for pivotal movement. Aspring I tends to hold the arm in the position shown. The end of arm IE4at the right, when viewed as in Figure 2, is provided with a downwardlyextending hook I95 that normally engages the threads in portion HM andtherefore whenever shaft 98 turns, it moves sleeve I02 lengthwise in adirection to the left.

Extending downwardly from the under surface of sleeve I92 is a lug I01that is perforated for the reception of a throttle control rod I08. Thisrod is provided with a stop I09 that is engaged by the lug-Iil1 when thelattermoves towards the left. The housing 99 is provided withlongitudinally extending slots III] and III through which the lugs III'IandI93 respectively extend. The throttle control rod is connected to anarm IIZ to which the butterfly valve pivot H3 is attached. When rod I08moves towards the left, the butterfly valve willopen. A spring I I4serves to'hold the throttle valve in a predetermined position, which iscontrolled by adjusting screw II5 Rod Iil8 has a threaded section IIB,to which a nut H1 is connected. This nut engages the" downwardlyextendingarm 54 ofthe bell crank lever and when rod I08 moves towardsthe left 'it turns the bell crank lever about its pivot and moves theupper abutment of spring 4? downwardly so as to increase the tension ofthis spring. Byincreasingthe spring tension the adjustment of thecentrifugal governor is effected. Valve 9i is operated by means of alever II8 that is nor mally held against the stop II9 by means of aspring I20. A screw I2 I is threadedly connected with the end of leverII8. Arm I3 is provided at its outer end with a plunger I22 that can bemoved-by means of a knob I23. A spring detent I24 holds the plungereither in extended position, as shown, or in its innermost position.When the plunger is moved int-o the arm, the latter can swing past thelever III} without engaging the latter. The purpose of the screw I2I isto adjust the point at which the lever I3 opens the valve 9I. i IExtending from the rotatable portion of valve 9 I is another lever whichhas been designated by reference numeral I25 and which carries anelectric contact I26 that is connected with one pole of the batteryI2'I. A stationary switch contact I28 is positioned above the movablecontact I26 andis connected to a lamp orother signal device I29bysuitablewires.

One pole of the battery is grounded at I30. When the valve opens, theswitch that has just been describedcloses, thereby lighting a signallamp which. apprises the operator that the automatic throttle controlmechanism is operating. Although a hydraulic motor 93 has been shown forturning shaft 95, it is to be understood that any mechanical equivalentcan be substituted, such as an electric motor whose operation can becontrolled by the switch at the end of lever I25.

Theautomatic control that has been described can be made inoperative bya downward movement of lever I04 and this lever maybeprovided with meansfor latching it in inoperative position. 'With the automa'ticmea'nsinoperative, the

throttle can be controlled manually by the means shown in Figure 5, inwhich reference numeral I3I designates a base to which a lever assemblycomprising an arcuate quadrant I32 is connected, by bolts I33. A leverI34 is pivoted at I35 which pivot is concentric with the arcuate surfaceI32. The throttle control rod I08 is pivotally connected with the leverat I36. Spring pressed friction member I3'I engages the surface I32 andis urged against the latter by means of a spring I38. The operator, bygrasping the handle I39 can move lever I34 to any desired position andthelever-twill be held against accidental movement by means of thefriction device. If desired, the adjustment can 'be efiected by means ofa foot operated pedal I40 which is pivoted at I4I. A linkI lZ connectsthe pedal with the lever I34. When the foot pedal is rocked about itspivot, it will move lever I34 to any desired position, and it istherefore possible to effect adjustment either by the handlellever, orbythe' foot operated pedal, or by the automatic means that .has beendescribed above. It may be said here thatthefriction device associatedwith the. adjusting lever shown in Figure5 is adjusted so that it canmove in response to the automatic mechanism.

Ilet us now assume that we have a construction like that shown on thedrawings and described herein and that the propeller shaft is rotatedfrom an internal combustion engine,the fuel supply to which iscontrolled by the throttle valve H3. The pitch of the propeller isadjusted to that mostsuitable for a take-off and when the engineandpropellershaft begin to rotate, the centrifugal governor'will be putinto operation. Since it isfrequently'necessary to run the en gine at ahigh speed'during take-off, it is essentialthat the governor be keptfrom functioning until the plane is inthe air, and therefore, be-

fore starting, the operator movesthe handle 86 into the full lineposition shown inFigure 4, and then movesSB in a vertical planewhereupon the shaft 44 with its attached slide valve 39 are held frommoving in response'to the forces exerted on shaft by the governor. Afterthe plane has reached the desired elevation,handle 86 can be moved toeither of the dotted line positions shown in Figure 4, whereupon shaft44 will be free to respond to the action of the governor. If the planeshould meet air currents they unload the propeller and reduce theresistance and the engine will naturally speed up, thereby increasingthe speed of governor rotatlon','whereuponthe slide valve will moveupwardly. When this upward movement becomes sufficient to 1111- coverthe ports-42:x:,,and 43w, port 40 will be covered and the 'oil from thepressure pump will then flow downwardly through opening 20, and into thespace I, thence through port 42a: and pipe 4211 to the intake ports 42of the hydraulic motor shown in Figure, 3 and the rotor Illa; of thelatter willthen begin to rotate in a clockwise direction so as toincrease the pitch of the blades, the oil exhausting through ports 43,43a, pipe 43y, opening a and M0. to sump II. When the hydraulic motoroperates, it turns shaft II and rotates the shafts 24 in a direction tomove the bearing pivots 29 forwardly when viewed as in Figure 1. Thisproduces a rearward movement of the connecting rod 3| and a clockwisemovement of arms 33 and 35. The position of arm-I3 is-so adjustedbymeans of the handle 11 that 11 if the pitch increase exceeds apredetermined value, arm i3 will engage the top of the spoollike member19 and limit its further upward movement and also move it, together withshaft 44 and the slide valve 35, downwardly into neutral position.

Since the speed of the driving motor is not constant, but varies withthe torque which it must exert on the propeller to obtain the desiredspeed of rotation, the rod 31 and the elements it drives become, whenthe craft is at a constant attitude or flying horizontally, an indicatorof the resistance of the craft to flight. With the higher resistance ofthe aircraft, it is necessary to open the throttle valve sufficiently toprovide the necessary extra amount of fuel. This opening of the throttlevalve is effected automatically by means comprising the valve 91, thehydraulic motor 93 and the movable sleeve H32 in a manner which has beendescribed. Therefore, when the pitch reaches a predetermined angle ofincrease, the automatic throttle control will function so as to increasethe fuel supply, whereupon the engine will be put into position todeliver the additional power necessary for the desired speed, of thecraft. In case of an emergency, or where the automatic control is notdesired, plunger l22'can be retracted into a position where it will notengage the lever H8 and the throttle controlled either by hand or by thefoot pedal I40 shown in Figure '5.

when this reaches a predetermined amount, the

slide valve-3'9 will move downwardly until port 43m is opened and portin closed, whereupon the oil will flow from chamber 20 through port 4 I,thence through port 43:1: and through pipe 43y to the intake ports 43 ofthe hydraulic motor. The motor will then rotate in a, counterclockwisedirection, whereupon the pitch of the blades will decrease, the oilexhausting through ports 42, 42x, pipe 42y, openings B and Ma to sump11. As the pitch decreases arms 33 and 35 will move counterclockwise andwhen the pitch .decrease has reached a predetermined limit, arm 35 willengage the adjustable stop ll, whereupon a force will be exerted whichmoves the shaft 44 and slide valve '39 upwardly so as to return them toneutral position. It will be seen that stop H can be adjusted downwardalong shaft 44 to serve as a low pitch. The neutral exhaust arrangementcomprising port 40, port 0 and recess h, will tend to avoid unnecessaryhunting by the governor controlled 'valve 39 during periods when theblades have the correct pitch, with the engine and propeller operatingunder "constant torque load.

' It will be observed that the automatic device for operating thethrottle valve does not function except when the parts are moving in adirection to increase the propeller pitch that is when resistance toflight has been substantially increased. At other times, the throttlevalve must be manually controlled by means of the mechanism shown inFigure 5 or some equivalent mechanism.

If, during flight the pilot finds it necessary to dispense with theautomatic pitch regulation .he can do so by moving the handle 86 intothe positionshown in full lines in Figure 4 and will then be in aposition to change the pitch manually 12 by tilting the lever aboutpivot 84. It is thus possible to take control away from the governor.

The pitch angles to which the propeller blades shall be limited can becontrolled, first by the adjustable stop 1 I, and then by the arm 73which can be adjusted about its pivot 12. It will be apparent that byspreading arms 35 and 13 a smaller lost motion is had between themovable arms and the stops 1! and 19 and by decreasing the lost motion,the blade pitch angles can be adjusted with greater nicety.

Instead of employing lever 86 during take-01f, this can be moved intoeither dotted line positions. Then after first moving I22 also intodotted line position, and with the engine running arm 73 can be moved ina downward direction against spool 79 until valve 39 is forced intoneutral position, after the blades have been reduced to the take-offpitch, thus leaving the governor free to reduce the blade pitch furtherin the event the propeller exerts enough torque load upon the engineduring take-off, and in this way avoid stalling the motor during suchperiods.

Screw IN is of such length as to cause a given percentage of increase inengine R. P. M., above a basic low rate of constant speed cruisingnumber of R. P. M., toward a higher crusing rate of engine R. P. M. tomaintain safe air speed regardless of wind conditions. In the drawingsthe nut I09 carried by rod [68 is to occupy the approximate positionshown with respect to lug H31 during the lower rate of constant speedpropeller operation. It is apparent that if the pilot so desires nut I09may be moved slightly to the left along rod I08, which will beequivalent to shortening screw illl. In this manner the percentage ofincrease in engine R. P. M. can be shortened to avoid increasing theengine R. P. M., unnecessarily. .Also, sufficient space should beprovided at the right of screw IC-l, to enable the pilot to move lug It!to the right, whereby the latter will not interfere with reducing theengine throttle when desired. A careful study will disclose that a faultwill be set up which will cause excessive engine R. P. M. if this screwlfil is too long, as hereinafter described.

In order to secure dependable operation, the cockpit of any given typeplane should carry a guide chart for the pilot to assure correctpresetting of member 73. Said chart to be based upon still air operationand horizontal flight, and to show what the blade pitch, plane velocityor air speed will normally be at any given altitude and plane loadfactor, at a given basic number of cruising engine R. P. M.

Thus, after the initial plane take-off and before the plane has reachedthe intended rate of cruising speed, the adjustabl arm 73 should bemoved by easy stages in an upward direction as fast as the plane picksup velocity and until it reaches normal cruising air speed. Whatever theplane velocity, air speed and blade pitch may be, they should be atpractically the same value time after time at a given altitude undersimilar still air flying conditions in horizontal flight, and

where arm 13 is preset one or more degrees ahead of this normal bladepitch position, arm 13 will not interfere with normal governor controlof pilot valve 39, under substantially or nearly still air operatingconditions.

Arm 13 should be reversed in a similar manner as engine R. P. M. isreduced with the plane approaching the vicinity of a landing field, toreduce the extent of lc-stmotion gap between arm 13 and spool 19, toenable the pilot to increas the number of engine R. P.M. should theoccasion arise without causing any material increase "in blade pitch.

Since arm 13 is atorque responsive element as well as a blade pitchlimiting element, it can be used to perform two different functions.Since this arm l3is moved in an upward direction with a decrease inblade pitch and downward with increase in blade pitch, it not only willmove the control valve 39 into neutral position when the blades reach apredetermined pitch angle, stopping the blade moving rotor Him, but itwill also at the same time actuate the control valve 9| to motor 93simultaneously, when a drop in propeller torque causes the governor toincrease the blade pitch to a predetermined angle limit.

Arm 13 thus being able to increase the number of engine and propeller R.P. M. commensurate with drop in propeller torque, together with theblades being allowed to advance one or more degrees above normal bladepitch, will so fully reload the propeller that the number of engine R.P. M. will be automatically reduced enough so that the governor willmove the motor control valve 39 in a direction to reduce the bladepitch, which action in turn will move arm l3 away from lever .I 18,allowing spring I2l to cut the source of power to stop motor 93 as soonas propeller torque value is fully restored to normal.

When the correct presetting of arm '13 is once established for normalstill air operation, and it is found that this setting does not causeoperation of motor 93, then when it is found that wind of anyappreciable velocity will cause operation of motor 93, and when it isfound that the increase in engine throttle will be increased inproportion to Wind velocity, or until propeller torque value is fullyrestored before motor 93 will be automatically stopped, such aperformance should be proof enough of the entire theory.

The above operation is based upon horizontal flight, as this appearsnecessary to establish a dependable working basis. However, angles offlight from horizontal will largely take care of themselves as, forinstance, in climbingat any particular angle the governor is left freeto reduce the blade pitch in accordance with ship drag and propellertorque action upon the engine, and if the plane is nosed downward into amore or less steep dive or glide, and the pilot does not care touse thepropeller as a brake against plane velocity, he can move arm 13 upwardtoward full feathering pitch position, and maintain a blade pitchcommensurate with plane velocity, by propeller torque and windmillaction.

Rod H18 interconnecting lever H2 and lever 54 will be found especiallyadvantageous for maintainingthe correct blade pitch, where the pilotfinds it necessary to increase the number of engine and propeller R. P.M. suddenly for any reason.

Rod ms connects throttle lever H2 and governorxlever 55. While thisarrangement will serve as an .aid to the pilot for quickly adjusting thenumber of engineR. P. M. with the manual means shown in Figure 5, itshould be employed in conjunction with an adjustable blade pitchlimiting means substantially as shown. If the latter is not employed inconnection therewith, and the pilot fails to increase the number ofengine R. P. M. promptly and commensurate with wind velocity when thelatter causes a drop in propeller torque, the governor will operate toincrease the blade pitch out ofcoordination with ship dragresistanca'and whereby the latter, together with 14 plane velocity, willdrop below a value com mensurate with the maintenance of a safe,predetermined rate of plane air speed. Where a preadjusted pitchlimiting means is provided, the lapse of time necessary for thiscondition to arise, can be entirely avoided,- at least within safelimits.

Where the cockpit chart shows, or the pilot knows, the extra number ofengine and propeller R. P. M. that is required to compensate for, say aten-mile per hour wind, then where the engine R. P. M. is automaticallyincreased by any given amount by action of the torque responsive elementincreasing the engine throttle, a pilot can determine wind velocity, aswell as plane velocity with respect to a land reference point merely bythe extra number of engine R. P. M. required before the torqueresponsive element automatically moves away from the engine throttlespeed increasing means H8.

To more fully explain the operation of the various parts, when a planeis flying at a rate above normal cruising speed, arm 13, throttle leverI34, valve H3, rod H38 and nut I09 will all have positions correspondingto the number of engine R. P. M. employed, which will leave nut I09 in aposition to the left of lug' till, leaving a gap between the latter andnut I09. Therefore, if screw Ill-l is designed to cause an increase inengine R. P. M. from a given base value to the R. P. M.'employed atnormal cruisingspeed, it

Will not be long enough to span this gap, andwill be unable to cause anyincrease in number of engine R. P. M., above that obtained by the firstmentioned throttle setting.

It is-when flying at a low altitude, low crusiing speed and "a basic lownumber of engine R. P. M., that screw it and motor 93 are intended tooperate as asafety factor, when the above mentioned parts will havepositions corresponding to those shown in the drawings. Under whichcondition the pilot will snap plunger 122 into operative position, andmove arm 13 downward to reduce the gap between these parts, and spool'19 and lever H8, and thus avoid having the blades being jumped out ofcoordination with plane velocity, and to insure an increase in thenumber of engine R. P. M., the instant it is required for maintaining asafe predetermined rate of plane velocity, to compensate for drops inpropeller torque, due to any appreciable change in the rate anddirection in movement of the air medium, and thereby insuring a rate ofplane velocity, equal in value to the planes minimumrate of air speed.Nut H can be adjusted with respect to arm 35 and pilot valve 39 to alterthe point of low,. or reverse blade pitch at which'arm 35 will movevalve 39 into neutral position, and by means of lever 88 valve 39 can bemoved into position for reversing the rotor was until the bladesaremoved through neutral pitch and on into reverse pitch angle of attackfor the purpose of using the engine and propeller as a brake in slowingdown plane velocity during landings, using brake 89 to maintain saidpitch position against the action of the governor regardless of thenumber ofpropeller R. P. M.

To avoid any misconception about the mechanism being fully operativewithin perfectly safe limits to the extent intended, it is believed adetailed description of the different methods of operationis advisable.

First, this mechanism is believed to beef special importance whereemployed in conjunction with an automatic pilot for holding a plane insubstantial .level flight, and which condition is intended to prevail inthe following explanations.

Second, it is intended to Operate to maintain a predetermined rate ofplane velocity with respect to a, given land reference point, equal invalue to the ,planes minimum rate of air speed. Unless means is providedto accomplish this purpose under the above mentioned level flightconditions, in the lower ranges of cruising speeds, the plane is quiteapt to be inadvertently converted more or less into a glider by movementof the air medium, and its efiect upon plane velocity, which conditionmight not be easily discernible by the pilot, is a matter which shouldnot be overlooked, since a glider with insuflicient or no engine power.is not believed adaptable for control by means of an automatic pilotfor obvious reasons. ,Since head wind velocity will have a definitebearing upon the predetermined rate of plane velocity, the latter isbelieved to be -a safety factor of utmost importance, and an object ofthe invention, which has not heretofore been fully brought out, :norgiven the attention it deserves.

A very important function resides in the mechanism comprising rod I08and nut H! for operatively interconnecting bell crank arms 53 and 54with lever H2 and throttle valve H3 for properly changing thecompression on spring ll, whereby a properly balanced relationship canbe maintained between the governor and any particular number of engineR. P. .M. resulting from movement of said rod I08, and whereby thenumber of engine R. P. M. can be changed from one rate of constant speedto another without disturbing the above mentioned balanced relationship.For the purpose of future reference this mechanism is identified by theletter W.

Propeller torque actionupon the above mechanism will cause the governorto operate motor Iflmin .either direction or to stop same as required tomaintain the desired balance relationship and coordination between bladepitch and plane velocity and ship drag requirements, regardless of thenumber of engine R. P. M. employed, provided motor 93 is operated toactuate throttle H3 substantially fast enough to compensate for anyquick drops in propeller torque as fast as they 'become set up. 'Theimportance of the latter will be observed in the following cases.

First assuming that the above-mentioned mechanism W is properly adjustedto produce satisfactory results in still air operation, then when planesare flying at comparatively low cruising speeds and altitudes, with thenumber of engine R. P. M. just sufficient to maintain a plane velocityat a rate safely above the planes mini-mum rate of air speed in stillair operation, the advantages to be gained tending towards safety andeconomical operation will readily become .apparent.

To avoid unnecessary hunting by the governor, the :main automaticcontrol resides in the bell crank arms '53 and 54 that are pivoted at55. Provided these arms are of suitable lengths, their constantrelat'ionshipfor coordinating the tension of spring 41 commensurate withany reciprocal movement of elements I08 and H2, will tend to constantlymaintain a balanced relationship between the number of engine R. P. M.and the governor, which relationship is very important if the governoris to move valve 3.9 for operating motor l or to either decrease orincrease-the blade pitch in accordance with any slight variations intorque value upon the engine, as .it should do under constantspeed-control.

With careful adjustment of nut l I! along element I 08 for loading thegovernor and in turn the engine as desired, this mechanism will,undersubstantially still air flying conditions, with the craft atconstant attitude, or in horizontal flight, cause the governor tooperate motor [01: to alter the blade pitch back andfor-th in accordancewith variations in torque, and will thus control the blade pitch withinpredetermined limits determined by the setting of adjustable arm 13,when the latter is preset fora given plan of flight. The movement ofvalve 39 into neutral position by means of rod 3|, and adjustable arm 13to stop motor i002, thus limiting the blade pitch, simultaneously as arm13 causes operation of motor 93 to increase the number of engine R. P.M., when arm l3 reaches a predetermined position, will bring both ofthese auxiliary automatic controls under the influence and direction ofmovement of rod 3| and arm 13, and since the movement of thesetwoelements are controlled by the governor, valve 39 and motor .93, willlikewise be controlled by the governor.

Opening of the throttle valve increases the power (in order to overcomethe greater drag on the craft due to a head wind, or the like, without:unduly lessening the air speed), which power must be absorbed by thepropeller, and since the power is dependent on the product of therotational speed of the propeller and the torque (or blade pitch) on thepropeller, a sufiicient increase in the rotational speed is provided forby the automatic setting of the governor bell crank arms 53 and '54 toprevent excessive and mutual hunting of the governor and the twoauxiliary controls.

Since the governor control-led arm 13, is adjustable during propelleroperation, it will enable the pilot to obtain the optimum blade pitch incombination with a given increase in number of engine R. P. M., and thusprevent any unnecessary hunting by the govern-or, said arm 13 beinggradually moved to a more advanced position as required to permit thegovernor to increase the blade pitch with any increase in the rate ofplane velocity, and thus avoid unnecessary hunting.

Where a plane is traveling at a comparatively high rate of velocity,therewill be less chance of plane-air speed dropping below the planesminimum requirements, for such a high rate of plane velocity can absorba certain amount of wind velocity without reducing plane velocity belowthe planes minimum rate of air speed.

If we figure :the lapse of time in which any given loss in planevelocity might become set up, and treat said lapse of timeas an unknownfactor, then we must come to the conclusion that the extent of anyresulting loss in plane velocityland air speed within a correspondinglapse of time will also become an unknown factor, and hazard, especiallyat low altitudes and reduced rates of engine R. P. .and plane air speed.

Radio reports, while important, cannot predict in :advancethe exacttime, place .or lapse of time during which such a hazard will become setup. A propeller torque responsive mechanism mounted for:automaticallyractuating the engine throttle when these causes produce adrop in propeller torque action "will compensate for such hazards thevery first instant they occur. Otherwise such hazards will remain acontinual threat to safety and progress in heavier than air flight, andsuch threat will .stand as a challenge to the most experienced pilot touse commensurate corrective measures beforeit is too late. It will be 17seen that even with an air speed as high as 140 R. P. M. planes may notbe entirely safe from such hazards, depending a lot of course uponaltitude,

to say nothing about shifting winds of higher velocity and theeconomical factors involved where high landing speeds are resorted to.Hence the need for some such automatic safety means as disclosed.

Any manual means such as shown in Figure 5 may, of course, be used forincreasing the number of engine R. P. M. instead of the automaticallyactuated means. However, where a plane is flying at some predeterminedlow engine R. P. M. and rate of plane air speed, at a low altitude,where any material drop in plane air speed might result in mishap, it isbelieved that said automatic means will have the advantage of avoidingguess work, carelessness and lapse of time before increasing the numberof engine R. P. M.the instant it is required, and which would becomparable to the timely operation of any automatic gear shift.

Duringhorizontal flight conditions it is well to keep in mind, that shipdrag resistance at any given plane air speed will be of the same valueflyinginto a head wind as when flying in still air operation. y

Even though a head wind willslow down'plane velocity, and willsubstitute its velocity to take the place of plane velocity, no changewill take place in ship drag resistance as long as plane air speed ismaintained. Since this isso, then provided a correct blade pitch angleof attach for a given ship drag resistance has any significance, itshould be at the same pitch angle in either case, in order to maintainplane velocity to a valve substantially equal to the planes minimum rateof air speed against the head wind, otherwise a safe rate of planevelocity will not be maintained.

It is wrong to allow a drop in propeller torque due to wind, to causethe governor to increase the blade pitch as the wind automatically slowsdown plane velocity, unless such is done in moderation andto a limitedextent only. In still air operation, the blade pitch will increase withincrease in plane velocity, and the pitch will decrease with a decreasein plane velocity. It is important to compare the direction of blademovement in the latter case with the direction of blade movement under ahead wind operation, in which case, unless the blade pitch is limited toa predetermined value,the pitch will increase as plane velocity isdecreased by the force of the wind. It will be seen that the directionof blade movement will b just opposite to the direction of blademovement in the still air operation, and by such change in direction ofblade movement it can be seen how a drop in propeller torque due to windwill set up a wide disparity in blade pitch with respect to planevelocity and ship drag.

Since the head wind will cause no decrease in ship drag resistanceprovided plane air speed is maintained, it will be seen how inconsistentit is to allow the governor to increase the blade pitch materially, ormore than enough to perform the additional function of automaticallyincreasing the number of engine R.P. M. to a higher constant speed rate,when the blades reach a predetermined pitch angle limit, therebyrestoring pro-' peller thrust and torque to a value commensurate withship drag resistance by increasing the rate of blade hitting speedrelative to the moving air medium. Thus maintaining a safe rate of planevelocity with respect to a land reference point,

a safe width by means of lever 11, the pilot can control the functionsmentionedin the correct proportions as desired, according to altitude,plane air speed, engine performance, etc., as flight conditions seem todictate in the interests of safety.

The pilot should be cautioned to guard against an extreme width of gapbetween the above identified members as during horizontal flight,otherwise a condition will exist as with a nonadjustable maximum "pitchlimiting means during flight,

in which a drop in propeller torque value upon the engine due to windwill cause the governor to increase or jump the blade pitch until torqueis fully restored, or until the maximum pitchlimiting means becomeseffective, which as explained may result in ablade pitch and thrustefficiency Way out of coordination with ship drag resistance, causingserious engine overload and automatic loss in plane velocity and airspeed.

Even in a tail wind, where the lost motion gap is too wide, a drop inpropeller torque may cause an increase or jump in blade pitch so wide asto absorb a large percentage of the engine power by torque resistance,when more of this power should be applied to propellerthrust action formaintaining plane velocity, which is synonymous with air speed and callsfor first consideration. This order of operation is important, since thegovernor cannot move the blades to occupy two different thrust positionsat the same instant.

In view of th foregoing, if ship dragresistance commensurate withmaintaining a given rate of plane air speed calls for a given bladethrust position, and a drop in propellertorque upon the engine due towind calls foran entirely different blade thrust position to furnishpropeller torque upon the engine, it can be seen how the governor willbe caught between two entirely different demands, only one of which canbe taken care of at a time. Since plane air speed and ship dragresistance is of paramount importance, and in the interests of safety,demands that the blade pitch shallnot be materially'altered. Then wherea drop in propeller torque due to wind demands an increase in bladepitch to restore propeller torque upon a the engine, we are confrontedwith a decision of whichdemand shall be taken care of. Bothdemands'cannot be taken care of simultaneously by merely altering theblade pitch. The drop in propeller torque must be taken care of insomeother way.

Where it is found that Wind causes the governor to increase the bladepitch for restoring propeller torque, we must come to the conclusionthat this drop in torque due to windmill action, is caused in the firstplace by a drop in the relative rate of blade hitting speed with respectto the moving air, and since the blade pitch should not be materiallyincreased when there is no change in ship drag resistance as mentionedabove, then we come to the final conclusion that an increase inthenumber of engine R. P. M. suflicient to restore propeller torque andthrust value is the only safe solution. If this is not done promptly,propeller torque and thrust value will remain below normal value,causing plane velocity and airspeed to automatically -drop accordingly,and the various factors cannot be maintained in coordinated relationshipwith respect to each otherfonmaintaining a predetermined safe rate ofplane velocity and air speed.

Windmill action due to a head wind W111 persist at a value commensuratewith wind velocity portion of the plane velocity to windvelocity, and

,planeair speed will drop in the same proportion. Thus, with the safetymechanism disclosed, it

wi l be p ss ble t f y at fa s ds s ht y ov safe minimum airspeedreguirements for still air on ra ionta s o a ma a in r a e tho imba o en ne a d p o e ler R. P. omm

rate with the rate and direction of movement of the ai ed. um o ubtantially mai a n n normal propeller torque and plane velocityregardless of wind conditions, all or which appears to be in line withthe laws ior generating forces :by respective rates of relativemovements.

I-Iowevertheabove is provided, the engine has then'ecessary availablenumber of B. ;P. M. above th t em o d fo main a n n minimum ai peed w twh h t om ens t for wind and to ma n in a lane ve c t e ual to min um aispeed, otherwise, pilot control must be resumed in time to takeadvantage of the law of gravity to n iplane e o t and airspeed where-r.e-'

guired to avoid .a forced landing.

he foregoing appears especially significant, since all planes regardlessof size and speed, must resort to areduced number of engineand propellerR, P. M. and rate of plane velocity during periods of approach, beforthe final lap and glide to a landing field.

When pilots speak of their plane hittin an air p ck t and d ppi se a hured fee t i pointedcut that similar drops in altitude may be due ,toconditions described herein. When ,such drops ,occur at low altitudes,occasional accidents are bound to result, unless wind velocity, andshifts in direction with respect to the plane are compensated forimmediately and without delay, otherwise plane velocity will not bemaintained at a ratein certain instances that is substantially equal .tominimum plane air speed.

Having described the invention what is claimed as n i? 1. In a device ofthe class described, in combination, a propeller having blades mountedfor pitch adjustment, means comprising an engine for rotating thepropeller, means for changing the speed and power of the engine,including :a throttle valve in the fuel supply of the engine, meanscomprising a motor for changing the blade pitch, control means for themotor, a governor mechanism for actuating the control means inaccordance with propeller speed, means for automatically actuating thecontrol means tostop the motor against the action of the governor whenthe pitch angle of :the blades has been increased to a predeterminedlimit, means for automatically moving'the engine throttle valve toincrease'the number of engine R. P. M. when the blades reach saidpredetermined pitch angle, means responsive gtO- movement .of saidgovernor to conform to the .change ,in number of engine R. P. M., andmeans operable by the operator for changing the effective position ofsaid blade pitch angle limit =during propeller operation,

2. In a device of the class described, in .com- ,bination, a propellerhaving blades mounted for pitch adjustment, means comprising an enginefor rotating the propeller, means for changing the speed and power ofthe engine, including a throttle valve in the fuel supply of the engine,means comprisinga motor for altering the blade pitch, control means forthe motor, a governor mechanism for actuating the control means for themotor, a governor mechanism for actuating .the control means inaccordance with propeller sp-eed, means for automatically actuating-thecontrol means to stop the motor, against the action of the governor,when the pitch angle of the blades have been increased to apredetermined pitch ,;m 1s c mp s ng a se ond mot means forautomatically operating said second motor to increase the enginethrottle valve opening when a drop in' propeller torque value upon theengine causes the blades to reach said predetermined pitch angle, meansresponsive to and commensurate with throttle valve movement forautomatically changing the operative characteristics of the speedresponsive governor ,to conform to the change in number of engine R. P.and means operable by the operator {for changing the operative positionof said predetermined vpitchangle during propeller operation.

3. In a device of the class described, in combination, a propellerhaving blades mounted for pitch adjustment, means comprising an enginefor rotating th propeller, .a throttle valve in the fuel supply of theengine for changing its speed and power, means comprising a speedresponsive, governor controlled motor for automatically changing thepitch of the blades in response :to propeller torque "resistance,automatic means for stopping theblade moving motor against the action ofthe governor, when the blades reach a predetermined pitch angle, meansoperable by the operator for changing said predetermined pitch angleduring propeller operation, means for moving the throttle valve, andmeans responsive to throttle valve movement interposed between the speedresponsive mechanism and the throtfile valve for stabilizing theoperative characteristics of the speed responsive mechanism :to conformto the various positions of the throttle valve and changes in number vofengine R. P. M.

4. In a ,device of .theflclassdescribed, in combination, a propellerhaving :blades mounted for pitch adjustment, means comprising. an enginefor rotating the propeller, means for changing the speed and power ofthe engine, including a throttle valve in the fuel supply of the engine,means comprising a speed responsive, governor controlled motorforlautom-atically' changing the pitch of rhea-blades in responseto.propeller torque resistance, means for operating the throttle valve,automatic means for. limiting the blade pitch to a predetermined anglevagainst the action of the governor, when the blades reach saidpredetermined pitch angle sald governor being provided withvcentrifugalweights, means for loading said weights, and means movablecommensurate with throttle valve. movement :Ior changing the load valueupon said weights toconform to change in the-number of engine R; P. M.for -maintaining 217 a substantially constant balanced relationshipbetween said governor and number of engine R. P. in coordination withthrottle valve movement, and means operable by the operator for changingsaid efiective predetermined blade pitch angle during propelleroperation.

5. In a device of the class described, in combination, a propellerhaving blades mounted for pitch adjustment, means comprising an enginefor rotating the propeller, means for changing the speed and power ofthe engine, including a throttle, valve in the fuel supply of theengine, means comprising a blade moving motor and a throttlemovingmotor, control means for each motor, a speed responsive governor forcontrolling the operation of said motors in accordance with propellerspeed and torque value upon the engine, automatic means for actuatingthe control means of said blade moving motor to stop the latter againstthe action of the governor, and for starting said throttle moving motorwhen th blades reach a predetermined pitch angle, means responsive tosaid throttle valve movement for automatically changing the operativecharacteristics of the speed responsive governor to conform with thechange in number of engine R. P. M. in accordance with throttle valvemovement, and means operable by the operator for changing said operativepredetermined blade pitch angle during propeller operation.

6. In a device of the class described, in combination, a propellerhaving blades mounted for pitch adjustment, an engine connected with thepropeller for rotating it, means for controlling the speed and the powerof the engine, including a throttle valve, a motor for changing theblade pitch, control means for the motor, a governor for actuating thecontrol means in accordance with propeller speed, means comprising ablade pitch responsive member for stopping the motor against the actionof the governor, when a drop in propeller torque value upon the enginecauses the governor to increase the blade pitch to a predetermined pitchangle limit, means for moving the engine throttle valve, meanscomprising an element responsive to and commensurate with throttle valvemovement for automatically changing the operative characteristics of thespeed responsive governor to conform with the change in numb-er ofengine R. P. M., whereby the governor will operate to decrease the bladepitch, when propeller torque action upon the en gine reaches a pointabove mean value, and means operable by the operator for changing thepredetermined pitch angle limit during propeller operation.

7. In a device of the class described, in combination, a propellerhaving blades mounted for pitch adjustment, an engine operativelyconnected with the propeller for rotating it, means for controlling thespeed and power of the engine to include a throttle valve, a motor foraltering the blade pitch, a source of power for the motor, control meansfor the latter, a speed responsive governor operatively associatedtherewith for normally altering the blade pitch in response tovariations in propeller speed, said control means including meanscomprising a power cutout element mounted for automatic actuation, whenthe blades reach a predetermined pitch angle, means comprising a bladepitch responsive element for actuating said cutout element to render themotor and governor ineffective to move the blades beyond saidpredetermined pitch angle, means operable by the operator as thepropeller operates for changing the blade pitch angle at which saidcutout element will be actuated, means for moving the engine throttlevalve, and means responsive to said throttle valve movement forautomatically changing the operative characteristics of the governor toconform to the change in number of engine and propeller R. P. M.

8. In a device of the class described, in combination, a propellerhaving blades mounted for pitch adjustment, an engine operativelyconnected with the propeller for rotating it, means comprising a motorfor altering the blade pitch, means for controllingthe operation of themotor, a governor, responsive to the speedof the engine and operativelyassociated with the motor control means, for changing the blade pitch inaccordance with engine speed, automatic means for stopping the motoragainst the action of the governor, when the blades reach apredetermined pitch angle, said governor being provided with centrifugalweights, means comprising a spring for loading said weights against theaction of centrifugal force acting upon them, a throttle valve in theengine fuel supply, means for automatically moving the throttle tochange the engine power when the blades reach said predetermined pitchangle, means comprising a throttle valve responsive element interposedbetween said governor sprin and throttle valve for altering thecompression upon said spring commensurate with throttle valve movement,for changing the load value of said spring upon said weights to providefor a change in number of engine R. P. M., substantially in accordancewith throttle valve movement, and means operable by the operator forchanging the effective predetermined blade pitch angle during propelleroperation.

9. In a propeller mechanism adapted to automatically maintain apredetermined rate of plane velocity, substantially equal to the planesminimum rate of air speed, comprising, in combination, a propellerhaving blades mounted for pitch adjustment, means comprising anenginefor rotating the propeller, means for changing the speed and power ofthe engine, including a throttle valve in the fuel supply of the engine,means comprising a motor for changing the blade pitch, control means forthe motor, a governor mechanism for actuating the control means inaccordance with propeller speed, means for automatically actuating thecontrol means to stop the motor against the action of the governor whenthe pitch angle of the blades has increased to a predetermined pitchangle, means for automatically moving the engine throttle valve toincrease the number of engine R. P. M. whenthe blades reach saidpredetermined pitch angle, means responsive to movement of said throttlevalve for automatically changing the operative characteristics of thespeed responsive governor to conform to the change in number of engineR. P. M., and means operable by the operator for changing the effectiveposition of said predetermined blade pitch angle during propelleroperation.

10. In a propeller mechanism adapted to automatically maintain apredetermined rate of craft velocity, substantially equal to the craftsminimum rate of air speed, comprising in combination, a propeller havingblades mounted for pitch adjustment, means comprising an engine forrotating the propeller, means for changing the speed and power of theengine, including a throttle valve in the fuel supply of the engine,means comprising a motor for changing the 'blade pitch, control meansfor the motor, a governor mechanisrrr foractuating. the .contrormeans inaccordance withzpropeller speed, means comprising an indicator mountedfor movement in response to craft resistancezto flight for automaticallyactuating the motor control means to stop the motor against the actionof thetgovernor, and foriauomatically moving the throttle valvecontrolmeans to increase the enginepower, when said indicator reachesa.predetermined position with respect to saidcontrol means,meansresponsive to throttle valve movement for automatically changing theoperative characteristics of the speed responsive governor to providefor a change in the number of engine R, P. M., and, means operable bythe operator during propeller operation for changing the,efiectivepredetermined position of saidindicator with respect to saidcontrol means.

. DANIEL G. LIILE-Y.

REFERENCES CITED The following references are of record in the file-ofthis patent:

UNITED STATES PATENTS

